Flasher



1959 J. R. HoLLlNs 2,919,424

FLASHER Filed Feb. 24. 1958 BATTERY INVENTOR.

- ATTOR Y United States Patent FLASHER Jesse R. Hollins, Brooklyn, N.Y., assignor to Signal-Stat Corporation, Brooklyn, N.Y., a corporation of New York Application February 24, 1958, Serial No. 717,164

4 Claims. (Cl. 340-81) This invention relates to thermally actuated circuit interrupters, commonly known as flashers, and more particularly to a novel flasher having its elements enclosed in an hermetically sealed translucent or transparent envelope and capable of functioning as a visible indication of flasher operation or pilot lamp.

Flashers are commonly used in the signalling systems of automotive vehicles, particularly in turn signalling circuits. Such flashers, as well as other thermomotive flashers, include a high resistance element which, upon a predetermined heating due to current flow therethrough, opens its own supply circuit and closes a supply circuit for signal lamps or the like. Sometimes the high resistance element, when heated, opens a signal lamp supply circuit.

When in fairly frequent or fairly constant operation, as when used in automotive vehicle turn signal systems, flashers are apt to malfunction due to contact deterioration and climatic elfects on the operating parts. It is known that contact life can be greatly increased if the contacts make and break, under load, in an hermetically sealed envelope from which air has been excluded. However, while it has been proposed to construct flashers in which the operating parts are enclosed in an hermetically sealed envelope, such constructions have been expensive in construction and liable to malfunctioning due to complications of the operating parts.

The usual automotive type of lamp bulb includes a base having a central contact and a peripheral contact surface, the base generally being of the bayonet type. When such a lamp bulb is inserted into a socket, the central contact makes contact with one terminal of an electric circuit and the peripheral contact makes contact with the opposite terminal, usually the grounding terminal.

Such lamps included an hermetically sealed envelope secured to the base and enclosing a high resistance filament supported between supply wires or legs projecting inwardly from the base and electrically connected to the base contacts.

In accordance with the present invention, a flasher is provided which includes a lamp construction of this type but with the addition of a normally open thermomotive circuit closer. This circuit closer is mounted on the base with its fixed end electrically connected to one supply wire or leg. The free end of the circuit closer extends toward but is normally spaced from the other supply wire or leg, and may carry a contact engageable with a contact on such other supply leg.

When an energizing circuit is closed, the filament becomes heated and glows, providing a visible light within the translucent or transparent envelope, which latter may either be evacuated or filled with an inert gas. The heat of the filament causes heating of the thermomotive member which thereupon operates to move its free end toward such other supply leg. When the thermomotive member makes electrical contact with such other supply leg, the filament is shunted and starts to cool. As a result, the

thermomotive member or element also cools and disengages such other supply leg, and the cycle then repeats.

When the high resistance element is not shunted by the thermomotive element, its resistance drop is sufiicient that there is insufiicient current flow to illuminate the signal lamp or lamps. However, with the thermomotive element shunting the filament, a low resistance lamp energizing circuit is provided and the signal lamps are effectively illuminated.

For an understanding of the invention principles, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawing. In the drawing the single figure is a combination part sectional view of the flasher and pilot lamp and schematic wiring diagram of the novel automotive turn signalling system.

Referring to the drawing, the combined flasher and pilot lamp unit 10 has the general appearance and constructional features of the usual single filament automotive lamp. Unit 10 has a dielectric base 11, with a conductive metal contact band 12 therearound, and a sealed glass envelope 13. While base 11 is illustrated as a bayonet type base, it will be understood that the base could equally well be a screw type base. Envelope 13 may be evacuated or may contain an inert gas.

Base 11 has the usual central contact 14 connected to a conductor 16 projecting as a support leg into envelope 13. Also, the usual conductor 17 is connected to contact band 12 and extends as a support leg into envelope 13 in spaced relation to conductor 16. The usual high resistance filament 15 is connected between the outer ends of conductors 16 and 17.

In accordance with the invention, a thermomotive element 20, such as a bimetallic strip is mounted in base 11 and electrically connected either to contact 14 or contact band 12. By way of example, element 20 is illustrated as electrically connected to contact 14 and thus to conductor 16. The projecting portion of element 20, within envelope 13, is bowed toward conductor 17. If desired, cooperable contacts 18 and '22 may be provided on conductor 17 and element 20. I

With the arrangement thus far described, when an electric potential is applied between contact band 12 and contact 14, the current flowing through high resistance filament 15 will cause the latter to heat and glow, thus heating the interior of envelope 13 and providing a source of light. The heat in envelope 13 causes thermomotive element '20 to expand and move its free end toward conductor 17. When element 20 engages conductor 17, or when contacts 18 and 22 engage, the high resistance filament 15 is shunted by the low resistance circuit comprising element 20 and conductor 17. Consequently, the light from envelope 13 is extinguished, filament 15 rapidly cools and, with the dissipation of heat from envelope 13, element 20 cools and contracts. This removes the shunt from filament 15 and the cycle repeats.

In the novel automotive turn signalling circuit, the combined flasher and pilot lamp unit 10 has its base 11 inserted into a metal socket 25 having a spring biased central contact 24 engaged by contact 14 and a metal side wall 26 engaged by contact band 12. A conductor 27 connects side wall 26 to the hot contact 28 of the usual grounded automotive battery 30, and a conductor 31 connects contact 24 to the movable contact 32 of a turn signal selector switch 35. Switch 35 has a fixed contact 33 connected to grounded left signal lamps LF and LR, and a fixed contact 34 connected to grounded right signal lamps RF and RR.

To signal a left turn, switch contact 32 is engaged with contact 33. This closes a circuit including high resistance filament 15, which latter beats and glows to light the unit 10. However, signal lamps LF and LR are not lit, as the resistance drop across filament 15 results in their being insufficient voltage to force full current through lamps LF and LR. When element Zll engages conductor 17, filament 15 is shunted and full current flows through lamps LF and LR. However, as filameat 15 is shunted, unit It) is no longer illuminated. Thus the pilot lamp unit i flashes in alternation with the main signal lamps. A corresponding operation recurs when switch arm 32 is engaged with contact 34.

By the described arrangement, the turn signalling circuit is greatly simplified as the flasher and pilot lamp are the same unit. At the same time, flasher contact life is greatly prolonged due to the contact enclosure in sealed envelope 13. The flasher is inexpensive and simple as it involves a relatively simple modification of a standard automotive lamp. It will be understood that the invention could also be incorporated in the type of automotive lamp having two base contacts.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the invention principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

' W at is claimed is:

1. An automotive turn signalling system comprising, in c mbination, a grounded source of electric potential; turn signal selector switch including a movable arm selectively engageable with either of a pair of fixed contacts; at least one grounded left turn signal lamp connected to one of said switch contacts; at least one grounded 1" ht turn signal lamp connected to the other of said swit a contact; a combined flasher and pilot lamp unit including a base, a sealed envelope of transparent material on said base, first and second contacts on said base, a pair of conductors each connected to a base contact and projecting into said envelope, a high resistance l 'nent connecting the ends of said conductors, and a thcrmomotive element connected to one of said base contacts and projecting into said envelope and having a free end normally spaced from said conductors; the free end of said element, when said element is heated, deflecting into engagement with the conductor connected to the other base contact to shunt said filament; means connecting one base contact to the ungrounded terminal of said source; and means connecting the other base contact to the arm of said switch; whereby, when the switch arm is engaged with either switch fixed contact, said filament Will heat and glow to heat said element and illuminute said unit with the corresponding signal lamps remaining nonilluminated due to the high resistance of said filament and said element, when heated, deflecting to so shunt said filament to extinguish the illumination of said unit and provide a low resistance illuminating .ircuit for said corresponding signal lamp; said filament thereupon cooling and said element cooling upon dissipation of the heat from said element to assume its initial position for repetition of the flashing cycle; said unit being illuminated in alternation with such corresponding signal lamp.

2. An automotive turn signalling system as claimed in claim 1 in which the free end of said element carries acontact engageable with a contact on the conductor connected to said other base contact.

3. An automotive turn signalling system as claimed in claim 1 in which said base has a central contact and a side contact, said element being connected to said central contact.

4. An. automotive turn signalling system as claimed in claim 1 in which said element is a bimetallic element.

2,665,963 Axelbcrg June 25, 1935 "[hielaclier Feb. 11, 1936 

